Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Stepper Motors 12 V Reference | B023A 02, B0233 06, B022A 06, B0223 06, B0408 06, B0418 06 | B0233 06, B022A 06, B0223 06, B0408 06, B0418 06 | -- | -- |
Mode Actuator Control 1 | B0233 06 | B0233 06 | B0233 01 | 1 |
Mode Actuator Control 2 | B0233 06 | B0233 06 | B0233 01 | 1 |
Mode Actuator Control 3 | B0233 06 | B0233 06 | B0233 01 | 1 |
Mode Actuator Control 4 | B0233 06 | B0233 06 | B0233 01 | 1 |
1. Air Distribution Malfunction | ||||
Circuit/System Description
With the defrost switch, air to foot well switch, air to windscreen switch and the air to head area switch at the HVAC control, the wished air distribution flap position can be put in. The selected value is sent to the HVAC control module via the LIN-Bus. The HVAC control module supplies a 12 V reference voltage to the stepper motor and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motor puts the air distribution flap into the selected position.
Diagnostic Aids
Check the following mechanical fault sources:
| • | Air distribution box |
| • | Air distribution hoses / air distributing ducts |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Automatic HVAC Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition ON, press and release the switch for air distribution to head. Verify the scan tool Front Defrost Switch parameter changes between Active and Inactive.
- Press and release the switch for air distribution to face. Verify the scan tool Instrument Panel Vents switch parameter changes between Active and Inactive.
- Press and release the switch for air distribution to floor. Verify the scan tool Floor Mode Switch parameter changes between Active and Inactive.
- Press and release the defrost switch. Verify the scan tool Enhanced Defrost Switch parameter changes between Active and Inactive.
- If all circuits test normal, replace the M37 Mode Actuator and verify the M37 Mode Actuator can be put into all positions. If the M37 Mode Actuator cannot be put into all positions, replace the K33 HVAC Control Module.
| ⇒ | If not the specified value, replace the A26 HVAC Control. |
| ⇒ | If not the specified value, replace the A26 HVAC Control. |
| ⇒ | If not the specified value, replace the A26 HVAC Control. |
| ⇒ | If not the specified value, replace the A26 HVAC Control. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for HVAC control module replacement, setup, and programming |
